What is base 64 encoding used for

Question

I ve heard people talking about  base 64 encoding  here and there   What is it used for

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It s used for converting arbitrary binary data to ASCII text   For example  e-mail attachments are sent this way

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Base64 encoding schemes are commonly used when there is a need to encode binary data that needs be stored and transferred over media that are designed to deal with textual data  This is to ensure that the data remains intact without modification during transport    Wiki  2017   Example could be the following  you have a web service that accept only ASCII chars  You want to save and then transfer user   s data to some other location  API  but recipient want receive untouched data  Base64 is for that       The only downside is that base64 encoding will require around 33   more space than regular strings   Another Example   uenc   url encoded   aHR0cDovL2xvYy5tYWdlbnRvLmNvbS9hc2ljcy1tZW4tcy1nZWwta2F5YW5vLXhpaS5odG1s   http   loc querytip com asics-men-s-gel-kayano-xii html   As you can see we can   t put char         in URL if we want to send last visited URL as parameter because we would break attribute value rule for    MOD rewrite        GET parameter   A full example would be     http   loc querytip com checkout cart add uenc http   loc magento com asics-men-s-gel-kayano-xii html product 93

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When you have some binary data that you want to ship across a network  you generally don t do it by just streaming the bits and bytes over the wire in a raw format   Why   because some media are made for streaming text   You never know -- some protocols may interpret your binary data as control characters  like a modem   or your binary data could be screwed up because the underlying protocol might think that you ve entered a special character combination  like how FTP translates line endings      So to get around this  people encode the binary data into characters   Base64 is one of these types of encodings     Why 64  Because you can generally rely on the same 64 characters being present in many character sets  and you can be reasonably confident that your data s going to end up on the other side of the wire uncorrupted

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When you have some binary data that you want to ship across a network  you generally don t do it by just streaming the bits and bytes over the wire in a raw format   Why   because some media are made for streaming text   You never know -- some protocols may interpret your binary data as control characters  like a modem   or your binary data could be screwed up because the underlying protocol might think that you ve entered a special character combination  like how FTP translates line endings      So to get around this  people encode the binary data into characters   Base64 is one of these types of encodings     Why 64  Because you can generally rely on the same 64 characters being present in many character sets  and you can be reasonably confident that your data s going to end up on the other side of the wire uncorrupted

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It s a textual encoding of binary data where the resultant text has nothing but letters  numbers and the symbols          and      It s a convenient way to store transmit binary data over media that is specifically used for textual data   But why Base-64  The two alternatives for converting binary data into text that immediately spring to mind are    Decimal  store the decimal value of each byte as three numbers  045 112 101 037 etc  where each byte is represented by 3 bytes  The data bloats three-fold  Hexadecimal  store the bytes as hex pairs  AC 47 0D 1A etc  where each byte is represented by 2 bytes  The data bloats two-fold    Base-64 maps 3 bytes  8 x 3   24 bits  in 4 characters that span 6-bits  6 x 4   24 bits   The result looks something like  TWFuIGlzIGRpc3Rpb      Therefore the bloating is only a mere  4 3   1 3333333 times the original

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From http   en wikipedia org wiki Base64      The term Base64 refers to a specific MIME content transfer encoding    It is also used as a generic term for any similar encoding scheme that   encodes binary data by treating it numerically and translating it into   a base 64 representation  The particular choice of base is due to the   history of character set encoding  one can choose a set of 64   characters that is both part of the subset common to most encodings    and also printable  This combination leaves the data unlikely to be   modified in transit through systems  such as email  which were   traditionally not 8-bit clean       Base64 can be used in a variety of contexts            Evolution and Thunderbird use Base64 to obfuscate e-mail passwords 1      Base64 can be used to transmit and store text that might otherwise cause delimiter collision     Base64 is often used as a quick but insecure shortcut to obscure secrets without incurring the overhead of cryptographic key management   Spammers use Base64 to evade basic anti-spamming tools  which often do not decode Base64 and therefore cannot detect keywords in encoded   messages      Base64 is used to encode character strings in LDIF files     Base64 is sometimes used to embed binary data in an XML file  using a syntax similar to        e g    Firefox s bookmarks html      Base64 is also used when communicating with government Fiscal Signature printing devices  usually  over serial or parallel ports  to   minimize the delay when transferring receipt characters for signing      Base64 is used to encode binary files such as images within scripts  to avoid depending on external files      Can be used to embed raw image data into a CSS property such as background-image

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Base-64 encoding is a way of taking binary data and turning it into text so that it s more easily transmitted in things like e-mail and HTML form data   http   en wikipedia org wiki Base64

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In the early days of computers  when telephone line inter-system communication was not particularly reliable  a quick  amp  dirty method of verifying data integrity was used   bit parity    In this method  every byte transmitted would have 7-bits of data  and the 8th would be 1 or 0  to force the total number of 1 bits in the byte to be even     Hence  0x01 would be transmited as 0x81  0x02 would be 0x82  0x03 would remain 0x03 etc   To further this system  when the ASCII character set was defined  only 00-7F were assigned characters    Still today  all characters set in the range 80-FF are non-standard   Many routers of the day put the parity check and byte translation into hardware  forcing the computers attached to them to deal strictly with 7-bit data   This force email attachments  and all other data  which is why HTTP  amp  SMTP protocols are text-based   to be convert into a text-only format   Few of the routers survived into the 90s   I severely doubt any of them are in use today

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Some transportation protocols only allow alphanumerical characters to be transmitted  Just imagine a situation where control characters are used to trigger special actions and or that only supports a limited bit width per character  Base64 transforms any input into an encoding that only uses alphanumeric characters       and the   as a padding character

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In the early days of computers  when telephone line inter-system communication was not particularly reliable  a quick  amp  dirty method of verifying data integrity was used   bit parity    In this method  every byte transmitted would have 7-bits of data  and the 8th would be 1 or 0  to force the total number of 1 bits in the byte to be even     Hence  0x01 would be transmited as 0x81  0x02 would be 0x82  0x03 would remain 0x03 etc   To further this system  when the ASCII character set was defined  only 00-7F were assigned characters    Still today  all characters set in the range 80-FF are non-standard   Many routers of the day put the parity check and byte translation into hardware  forcing the computers attached to them to deal strictly with 7-bit data   This force email attachments  and all other data  which is why HTTP  amp  SMTP protocols are text-based   to be convert into a text-only format   Few of the routers survived into the 90s   I severely doubt any of them are in use today

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The usage of Base64 I m going to describe here is somewhat a hack  So if you don t like hacks  please do not go on   I went into trouble when I discovered that MySQL s utf8 does not support 4-byte unicode characters since it uses a 3-byte version of utf8  So what I did to support full 4-byte unicode over MySQL s utf8  Well  base64 encode strings when storing into the database and base64 decode when retrieving   Since base64 encoding and decoding is very fast  the above worked perfectly   You have the following points to take note of    Base64 encoding uses 33  more storage Strings stored in the database wont be human readable  You could sell that as a feature that database strings use a basic form of encryption     You could use the above method for any storage engine that does not support unicode

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From http   en wikipedia org wiki Base64      The term Base64 refers to a specific MIME content transfer encoding    It is also used as a generic term for any similar encoding scheme that   encodes binary data by treating it numerically and translating it into   a base 64 representation  The particular choice of base is due to the   history of character set encoding  one can choose a set of 64   characters that is both part of the subset common to most encodings    and also printable  This combination leaves the data unlikely to be   modified in transit through systems  such as email  which were   traditionally not 8-bit clean       Base64 can be used in a variety of contexts            Evolution and Thunderbird use Base64 to obfuscate e-mail passwords 1      Base64 can be used to transmit and store text that might otherwise cause delimiter collision     Base64 is often used as a quick but insecure shortcut to obscure secrets without incurring the overhead of cryptographic key management   Spammers use Base64 to evade basic anti-spamming tools  which often do not decode Base64 and therefore cannot detect keywords in encoded   messages      Base64 is used to encode character strings in LDIF files     Base64 is sometimes used to embed binary data in an XML file  using a syntax similar to        e g    Firefox s bookmarks html      Base64 is also used when communicating with government Fiscal Signature printing devices  usually  over serial or parallel ports  to   minimize the delay when transferring receipt characters for signing      Base64 is used to encode binary files such as images within scripts  to avoid depending on external files      Can be used to embed raw image data into a CSS property such as background-image

User · Answer

Base64  Base64 is a generic term for a number of similar encoding schemes that encode binary data by treating it numerically and translating it into a base 64 representation  The Base64 term originates from a specific MIME content transfer encoding   Base64 encoding schemes are commonly used when there is a need to encode binary data that needs be stored and transferred over media that are designed to deal with textual data  This is to ensure that the data remains intact without modification during transport  Base64 is used commonly in a number of applications including email via MIME  and storing complex data in XML

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Base64 can be used for many purposes    The primary reason is to convert binary data to something passable   I sometimes use it to pass JSON data around from one site to another  store information in cookies about a user   Note  You  can  use it for encryption - I don t see why people say you can t  and that it s not encryption  although it would be easily breakable and is frowned upon  Encryption means nothing more than converting one string of data to another string of data that can be either later decrypted or not  and that s what base64 does

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It s basically a way of encoding arbitrary binary data in ASCII text  It takes 4 characters per 3 bytes of data  plus potentially a bit of padding at the end   Essentially each 6 bits of the input is encoded in a 64-character alphabet  The  standard  alphabet uses A-Z  a-z  0-9 and   and    with   as a padding character  There are URL-safe variants   Wikipedia is a reasonably good source of more information

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Base64  Base64 is a generic term for a number of similar encoding schemes that encode binary data by treating it numerically and translating it into a base 64 representation  The Base64 term originates from a specific MIME content transfer encoding   Base64 encoding schemes are commonly used when there is a need to encode binary data that needs be stored and transferred over media that are designed to deal with textual data  This is to ensure that the data remains intact without modification during transport  Base64 is used commonly in a number of applications including email via MIME  and storing complex data in XML

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Aside from what s already been said  two very common uses that have not been listed are  Hashes   Hashes are one-way functions that transform a block of bytes into another block of bytes of a fixed size such as 128bit or 256bit  SHA MD5   Converting the resulting bytes into Base64 makes it much easier to display the hash especially when you are comparing a checksum for integrity  Hashes are so often seen in Base64 that many people mistake Base64 itself as a hash   Cryptography   Since an encryption key does not have to be text but raw bytes it is sometimes necessary to store it in a file or database  which Base64 comes in handy for  Same with the resulting encrypted bytes   Note that although Base64 is often used in cryptography is not a security mechanism  Anyone can convert the Base64 string back to its original bytes  so it should not be used as a means for protecting data  only as a format to display or store raw bytes more easily   Certificates  x509 certificates in PEM format are base 64 encoded  http   how2ssl com articles working with pem files

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Aside from what s already been said  two very common uses that have not been listed are  Hashes   Hashes are one-way functions that transform a block of bytes into another block of bytes of a fixed size such as 128bit or 256bit  SHA MD5   Converting the resulting bytes into Base64 makes it much easier to display the hash especially when you are comparing a checksum for integrity  Hashes are so often seen in Base64 that many people mistake Base64 itself as a hash   Cryptography   Since an encryption key does not have to be text but raw bytes it is sometimes necessary to store it in a file or database  which Base64 comes in handy for  Same with the resulting encrypted bytes   Note that although Base64 is often used in cryptography is not a security mechanism  Anyone can convert the Base64 string back to its original bytes  so it should not be used as a means for protecting data  only as a format to display or store raw bytes more easily   Certificates  x509 certificates in PEM format are base 64 encoded  http   how2ssl com articles working with pem files

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Some transportation protocols only allow alphanumerical characters to be transmitted  Just imagine a situation where control characters are used to trigger special actions and or that only supports a limited bit width per character  Base64 transforms any input into an encoding that only uses alphanumeric characters       and the   as a padding character

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One hexadecimal digit is of one nibble  4 bits   Two nibbles make 8 bits which are also called 1 byte   MD5 generates a 128-bit output which is represented using a sequence of 32 hexadecimal digits  which in turn are 32 4 128 bits  128 bits make 16 bytes  since 1 byte is 8 bits    Each Base64 character encodes 6 bits  except the last non-pad character which can encode 2  4 or 6 bits  and final pad characters  if any   Therefore  per Base64 encoding  a 128-bit hash requires at least  128 6    22 characters  plus pad if any   Using base64  we can produce the encoded output of our desired length  6  8  or 10    If we choose to decide 8 char long output  it occupies only 8 bytes whereas it was occupying 16 bytes for 128-bit hash output   So  in addition to security  base64 encoding is also used to reduce the space consumed

User · Answer

It s a textual encoding of binary data where the resultant text has nothing but letters  numbers and the symbols          and      It s a convenient way to store transmit binary data over media that is specifically used for textual data   But why Base-64  The two alternatives for converting binary data into text that immediately spring to mind are    Decimal  store the decimal value of each byte as three numbers  045 112 101 037 etc  where each byte is represented by 3 bytes  The data bloats three-fold  Hexadecimal  store the bytes as hex pairs  AC 47 0D 1A etc  where each byte is represented by 2 bytes  The data bloats two-fold    Base-64 maps 3 bytes  8 x 3   24 bits  in 4 characters that span 6-bits  6 x 4   24 bits   The result looks something like  TWFuIGlzIGRpc3Rpb      Therefore the bloating is only a mere  4 3   1 3333333 times the original

User · Answer

The usage of Base64 I m going to describe here is somewhat a hack  So if you don t like hacks  please do not go on   I went into trouble when I discovered that MySQL s utf8 does not support 4-byte unicode characters since it uses a 3-byte version of utf8  So what I did to support full 4-byte unicode over MySQL s utf8  Well  base64 encode strings when storing into the database and base64 decode when retrieving   Since base64 encoding and decoding is very fast  the above worked perfectly   You have the following points to take note of    Base64 encoding uses 33  more storage Strings stored in the database wont be human readable  You could sell that as a feature that database strings use a basic form of encryption     You could use the above method for any storage engine that does not support unicode

User · Answer

Base-64 encoding is a way of taking binary data and turning it into text so that it s more easily transmitted in things like e-mail and HTML form data   http   en wikipedia org wiki Base64

User · Answer

It s used for converting arbitrary binary data to ASCII text   For example  e-mail attachments are sent this way

User · Answer

From http   en wikipedia org wiki Base64      The term Base64 refers to a specific MIME content transfer encoding    It is also used as a generic term for any similar encoding scheme that   encodes binary data by treating it numerically and translating it into   a base 64 representation  The particular choice of base is due to the   history of character set encoding  one can choose a set of 64   characters that is both part of the subset common to most encodings    and also printable  This combination leaves the data unlikely to be   modified in transit through systems  such as email  which were   traditionally not 8-bit clean       Base64 can be used in a variety of contexts            Evolution and Thunderbird use Base64 to obfuscate e-mail passwords 1      Base64 can be used to transmit and store text that might otherwise cause delimiter collision     Base64 is often used as a quick but insecure shortcut to obscure secrets without incurring the overhead of cryptographic key management   Spammers use Base64 to evade basic anti-spamming tools  which often do not decode Base64 and therefore cannot detect keywords in encoded   messages      Base64 is used to encode character strings in LDIF files     Base64 is sometimes used to embed binary data in an XML file  using a syntax similar to        e g    Firefox s bookmarks html      Base64 is also used when communicating with government Fiscal Signature printing devices  usually  over serial or parallel ports  to   minimize the delay when transferring receipt characters for signing      Base64 is used to encode binary files such as images within scripts  to avoid depending on external files      Can be used to embed raw image data into a CSS property such as background-image

User · Answer

One hexadecimal digit is of one nibble  4 bits   Two nibbles make 8 bits which are also called 1 byte   MD5 generates a 128-bit output which is represented using a sequence of 32 hexadecimal digits  which in turn are 32 4 128 bits  128 bits make 16 bytes  since 1 byte is 8 bits    Each Base64 character encodes 6 bits  except the last non-pad character which can encode 2  4 or 6 bits  and final pad characters  if any   Therefore  per Base64 encoding  a 128-bit hash requires at least  128 6    22 characters  plus pad if any   Using base64  we can produce the encoded output of our desired length  6  8  or 10    If we choose to decide 8 char long output  it occupies only 8 bytes whereas it was occupying 16 bytes for 128-bit hash output   So  in addition to security  base64 encoding is also used to reduce the space consumed

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To expand a bit on what Brad is saying  many transport mechanisms for email and Usenet and other ways of moving data are not  8 bit clean   which means that characters outside the standard ascii character set might be mangled in transit - for instance  0x0D might be seen as a carriage return  and turned into a carriage return and line feed   Base 64 maps all the binary characters into several standard ascii letters and numbers and punctuation so they won t be mangled this way

User · Answer

It s a textual encoding of binary data where the resultant text has nothing but letters  numbers and the symbols          and      It s a convenient way to store transmit binary data over media that is specifically used for textual data   But why Base-64  The two alternatives for converting binary data into text that immediately spring to mind are    Decimal  store the decimal value of each byte as three numbers  045 112 101 037 etc  where each byte is represented by 3 bytes  The data bloats three-fold  Hexadecimal  store the bytes as hex pairs  AC 47 0D 1A etc  where each byte is represented by 2 bytes  The data bloats two-fold    Base-64 maps 3 bytes  8 x 3   24 bits  in 4 characters that span 6-bits  6 x 4   24 bits   The result looks something like  TWFuIGlzIGRpc3Rpb      Therefore the bloating is only a mere  4 3   1 3333333 times the original

User · Answer

It s a textual encoding of binary data where the resultant text has nothing but letters  numbers and the symbols          and      It s a convenient way to store transmit binary data over media that is specifically used for textual data   But why Base-64  The two alternatives for converting binary data into text that immediately spring to mind are    Decimal  store the decimal value of each byte as three numbers  045 112 101 037 etc  where each byte is represented by 3 bytes  The data bloats three-fold  Hexadecimal  store the bytes as hex pairs  AC 47 0D 1A etc  where each byte is represented by 2 bytes  The data bloats two-fold    Base-64 maps 3 bytes  8 x 3   24 bits  in 4 characters that span 6-bits  6 x 4   24 bits   The result looks something like  TWFuIGlzIGRpc3Rpb      Therefore the bloating is only a mere  4 3   1 3333333 times the original

User · Answer

To expand a bit on what Brad is saying  many transport mechanisms for email and Usenet and other ways of moving data are not  8 bit clean   which means that characters outside the standard ascii character set might be mangled in transit - for instance  0x0D might be seen as a carriage return  and turned into a carriage return and line feed   Base 64 maps all the binary characters into several standard ascii letters and numbers and punctuation so they won t be mangled this way

User · Answer

Base-64 encoding is a way of taking binary data and turning it into text so that it s more easily transmitted in things like e-mail and HTML form data   http   en wikipedia org wiki Base64

User · Answer

It s basically a way of encoding arbitrary binary data in ASCII text  It takes 4 characters per 3 bytes of data  plus potentially a bit of padding at the end   Essentially each 6 bits of the input is encoded in a 64-character alphabet  The  standard  alphabet uses A-Z  a-z  0-9 and   and    with   as a padding character  There are URL-safe variants   Wikipedia is a reasonably good source of more information

User · Answer

Base64 can be used for many purposes    The primary reason is to convert binary data to something passable   I sometimes use it to pass JSON data around from one site to another  store information in cookies about a user   Note  You  can  use it for encryption - I don t see why people say you can t  and that it s not encryption  although it would be easily breakable and is frowned upon  Encryption means nothing more than converting one string of data to another string of data that can be either later decrypted or not  and that s what base64 does

User · Answer

From http   en wikipedia org wiki Base64      The term Base64 refers to a specific MIME content transfer encoding    It is also used as a generic term for any similar encoding scheme that   encodes binary data by treating it numerically and translating it into   a base 64 representation  The particular choice of base is due to the   history of character set encoding  one can choose a set of 64   characters that is both part of the subset common to most encodings    and also printable  This combination leaves the data unlikely to be   modified in transit through systems  such as email  which were   traditionally not 8-bit clean       Base64 can be used in a variety of contexts            Evolution and Thunderbird use Base64 to obfuscate e-mail passwords 1      Base64 can be used to transmit and store text that might otherwise cause delimiter collision     Base64 is often used as a quick but insecure shortcut to obscure secrets without incurring the overhead of cryptographic key management   Spammers use Base64 to evade basic anti-spamming tools  which often do not decode Base64 and therefore cannot detect keywords in encoded   messages      Base64 is used to encode character strings in LDIF files     Base64 is sometimes used to embed binary data in an XML file  using a syntax similar to        e g    Firefox s bookmarks html      Base64 is also used when communicating with government Fiscal Signature printing devices  usually  over serial or parallel ports  to   minimize the delay when transferring receipt characters for signing      Base64 is used to encode binary files such as images within scripts  to avoid depending on external files      Can be used to embed raw image data into a CSS property such as background-image

User · Answer

Mostly  I ve seen it used to encode binary data in contexts that can only handle ascii - or a simple - character sets

User · Answer

When you have some binary data that you want to ship across a network  you generally don t do it by just streaming the bits and bytes over the wire in a raw format   Why   because some media are made for streaming text   You never know -- some protocols may interpret your binary data as control characters  like a modem   or your binary data could be screwed up because the underlying protocol might think that you ve entered a special character combination  like how FTP translates line endings      So to get around this  people encode the binary data into characters   Base64 is one of these types of encodings     Why 64  Because you can generally rely on the same 64 characters being present in many character sets  and you can be reasonably confident that your data s going to end up on the other side of the wire uncorrupted

User · Answer

Some transportation protocols only allow alphanumerical characters to be transmitted  Just imagine a situation where control characters are used to trigger special actions and or that only supports a limited bit width per character  Base64 transforms any input into an encoding that only uses alphanumeric characters       and the   as a padding character

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I use it in a practical sense when we transfer large binary objects  images  via web services  So when I am testing a C  web service using a python script  the binary object can be recreated with a little magic       In python   import base64 imageAsBytes   base64 b64decode  dataFromWS

User · Answer

When you have some binary data that you want to ship across a network  you generally don t do it by just streaming the bits and bytes over the wire in a raw format   Why   because some media are made for streaming text   You never know -- some protocols may interpret your binary data as control characters  like a modem   or your binary data could be screwed up because the underlying protocol might think that you ve entered a special character combination  like how FTP translates line endings      So to get around this  people encode the binary data into characters   Base64 is one of these types of encodings     Why 64  Because you can generally rely on the same 64 characters being present in many character sets  and you can be reasonably confident that your data s going to end up on the other side of the wire uncorrupted

User · Answer

Mostly  I ve seen it used to encode binary data in contexts that can only handle ascii - or a simple - character sets

User · Answer

It s used for converting arbitrary binary data to ASCII text   For example  e-mail attachments are sent this way

User · Answer

Base64 encoding schemes are commonly used when there is a need to encode binary data that needs be stored and transferred over media that are designed to deal with textual data  This is to ensure that the data remains intact without modification during transport    Wiki  2017   Example could be the following  you have a web service that accept only ASCII chars  You want to save and then transfer user   s data to some other location  API  but recipient want receive untouched data  Base64 is for that       The only downside is that base64 encoding will require around 33   more space than regular strings   Another Example   uenc   url encoded   aHR0cDovL2xvYy5tYWdlbnRvLmNvbS9hc2ljcy1tZW4tcy1nZWwta2F5YW5vLXhpaS5odG1s   http   loc querytip com asics-men-s-gel-kayano-xii html   As you can see we can   t put char         in URL if we want to send last visited URL as parameter because we would break attribute value rule for    MOD rewrite        GET parameter   A full example would be     http   loc querytip com checkout cart add uenc http   loc magento com asics-men-s-gel-kayano-xii html product 93

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I use it in a practical sense when we transfer large binary objects  images  via web services  So when I am testing a C  web service using a python script  the binary object can be recreated with a little magic       In python   import base64 imageAsBytes   base64 b64decode  dataFromWS

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Years ago  when mailing functionality was introduced  so that was utterly text based  as the time passed  need for attachments like image and media  audio video etc  came into existence  When these attachments are sent over internet  which is basically in the form of binary data   the probability of binary data getting corrupt is high in its raw form  So  to tackle this problem BASE64 came along   The problem with binary data is that it contains null characters which in some languages like C C   represent end of character string so sending binary data in raw form containing NULL bytes will stop a file from being fully read and lead in a corrupt data   For Example    In C and C    this  null  character shows the end of a string  So  HELLO  is stored like this   H E L L O  72 69 76 76 79 00  The 00 says  stop here    Now let   s dive into how BASE64 encoding works   Point to be noted   Length of the string should be in multiple of 3   Example 1    String to be encoded      ace     Length 3  1  Convert each character to decimal   a  97  c  99  e  101    2  Change each decimal to 8-bit binary representation   97  01100001  99  01100011  101  01100101  Combined   01100001 01100011 01100101  3  Seperate in a group of 6-bit   011000 010110 001101 100101  4  Calculate binary to decimal  011000  24  010110  22  001101  13  100101  37  5  Covert decimal characters to base64 using base64 chart   24  Y  22  W  13  N  37  l     ace          YWNl       Example 2    String to be encoded      abcd    Length 4  it s not multiple of 3  So to make string length multiple of 3   we must add 2 bit padding to make length  6  Padding bit is represented by         sign   Point to be noted   One padding bit equals two zeroes 00 so two padding bit equals four zeroes 0000   So lets start the process       1  Convert each character to decimal   a  97  b  98  c  99  d  100  2  Change each decimal to 8-bit binary representation   97  01100001  98  01100010  99  01100011  100  01100100  3  Separate in a group of 6-bit   011000  010110  001001  100011  011001  00  so the last 6-bit is not complete so we insert two padding bit which equals four zeroes    0000      011000  010110  001001  100011  011001  000000     Now  it is equal  Two equals sign at the end show that 4 zeroes were added  helps in decoding    4  Calculate binary to decimal   011000  24  010110  22  001001  9  100011  35  011001  25  000000 0     5  Covert decimal characters to base64 using base64 chart   24  Y  22  W  9  j  35  j  25  Z  0  A        abcd          YWJjZA

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It s used for converting arbitrary binary data to ASCII text   For example  e-mail attachments are sent this way

User · Answer

Mostly  I ve seen it used to encode binary data in contexts that can only handle ascii - or a simple - character sets

User · Answer

It s basically a way of encoding arbitrary binary data in ASCII text  It takes 4 characters per 3 bytes of data  plus potentially a bit of padding at the end   Essentially each 6 bits of the input is encoded in a 64-character alphabet  The  standard  alphabet uses A-Z  a-z  0-9 and   and    with   as a padding character  There are URL-safe variants   Wikipedia is a reasonably good source of more information

User · Answer

In the early days of computers  when telephone line inter-system communication was not particularly reliable  a quick  amp  dirty method of verifying data integrity was used   bit parity    In this method  every byte transmitted would have 7-bits of data  and the 8th would be 1 or 0  to force the total number of 1 bits in the byte to be even     Hence  0x01 would be transmited as 0x81  0x02 would be 0x82  0x03 would remain 0x03 etc   To further this system  when the ASCII character set was defined  only 00-7F were assigned characters    Still today  all characters set in the range 80-FF are non-standard   Many routers of the day put the parity check and byte translation into hardware  forcing the computers attached to them to deal strictly with 7-bit data   This force email attachments  and all other data  which is why HTTP  amp  SMTP protocols are text-based   to be convert into a text-only format   Few of the routers survived into the 90s   I severely doubt any of them are in use today

User · Answer

Some transportation protocols only allow alphanumerical characters to be transmitted  Just imagine a situation where control characters are used to trigger special actions and or that only supports a limited bit width per character  Base64 transforms any input into an encoding that only uses alphanumeric characters       and the   as a padding character

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To expand a bit on what Brad is saying  many transport mechanisms for email and Usenet and other ways of moving data are not  8 bit clean   which means that characters outside the standard ascii character set might be mangled in transit - for instance  0x0D might be seen as a carriage return  and turned into a carriage return and line feed   Base 64 maps all the binary characters into several standard ascii letters and numbers and punctuation so they won t be mangled this way

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To expand a bit on what Brad is saying  many transport mechanisms for email and Usenet and other ways of moving data are not  8 bit clean   which means that characters outside the standard ascii character set might be mangled in transit - for instance  0x0D might be seen as a carriage return  and turned into a carriage return and line feed   Base 64 maps all the binary characters into several standard ascii letters and numbers and punctuation so they won t be mangled this way

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It s basically a way of encoding arbitrary binary data in ASCII text  It takes 4 characters per 3 bytes of data  plus potentially a bit of padding at the end   Essentially each 6 bits of the input is encoded in a 64-character alphabet  The  standard  alphabet uses A-Z  a-z  0-9 and   and    with   as a padding character  There are URL-safe variants   Wikipedia is a reasonably good source of more information

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I use it in a practical sense when we transfer large binary objects  images  via web services  So when I am testing a C  web service using a python script  the binary object can be recreated with a little magic       In python   import base64 imageAsBytes   base64 b64decode  dataFromWS

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I use it in a practical sense when we transfer large binary objects  images  via web services  So when I am testing a C  web service using a python script  the binary object can be recreated with a little magic       In python   import base64 imageAsBytes   base64 b64decode  dataFromWS

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In the early days of computers  when telephone line inter-system communication was not particularly reliable  a quick  amp  dirty method of verifying data integrity was used   bit parity    In this method  every byte transmitted would have 7-bits of data  and the 8th would be 1 or 0  to force the total number of 1 bits in the byte to be even     Hence  0x01 would be transmited as 0x81  0x02 would be 0x82  0x03 would remain 0x03 etc   To further this system  when the ASCII character set was defined  only 00-7F were assigned characters    Still today  all characters set in the range 80-FF are non-standard   Many routers of the day put the parity check and byte translation into hardware  forcing the computers attached to them to deal strictly with 7-bit data   This force email attachments  and all other data  which is why HTTP  amp  SMTP protocols are text-based   to be convert into a text-only format   Few of the routers survived into the 90s   I severely doubt any of them are in use today

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Years ago  when mailing functionality was introduced  so that was utterly text based  as the time passed  need for attachments like image and media  audio video etc  came into existence  When these attachments are sent over internet  which is basically in the form of binary data   the probability of binary data getting corrupt is high in its raw form  So  to tackle this problem BASE64 came along   The problem with binary data is that it contains null characters which in some languages like C C   represent end of character string so sending binary data in raw form containing NULL bytes will stop a file from being fully read and lead in a corrupt data   For Example    In C and C    this  null  character shows the end of a string  So  HELLO  is stored like this   H E L L O  72 69 76 76 79 00  The 00 says  stop here    Now let   s dive into how BASE64 encoding works   Point to be noted   Length of the string should be in multiple of 3   Example 1    String to be encoded      ace     Length 3  1  Convert each character to decimal   a  97  c  99  e  101    2  Change each decimal to 8-bit binary representation   97  01100001  99  01100011  101  01100101  Combined   01100001 01100011 01100101  3  Seperate in a group of 6-bit   011000 010110 001101 100101  4  Calculate binary to decimal  011000  24  010110  22  001101  13  100101  37  5  Covert decimal characters to base64 using base64 chart   24  Y  22  W  13  N  37  l     ace          YWNl       Example 2    String to be encoded      abcd    Length 4  it s not multiple of 3  So to make string length multiple of 3   we must add 2 bit padding to make length  6  Padding bit is represented by         sign   Point to be noted   One padding bit equals two zeroes 00 so two padding bit equals four zeroes 0000   So lets start the process       1  Convert each character to decimal   a  97  b  98  c  99  d  100  2  Change each decimal to 8-bit binary representation   97  01100001  98  01100010  99  01100011  100  01100100  3  Separate in a group of 6-bit   011000  010110  001001  100011  011001  00  so the last 6-bit is not complete so we insert two padding bit which equals four zeroes    0000      011000  010110  001001  100011  011001  000000     Now  it is equal  Two equals sign at the end show that 4 zeroes were added  helps in decoding    4  Calculate binary to decimal   011000  24  010110  22  001001  9  100011  35  011001  25  000000 0     5  Covert decimal characters to base64 using base64 chart   24  Y  22  W  9  j  35  j  25  Z  0  A        abcd          YWJjZA

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Mostly  I ve seen it used to encode binary data in contexts that can only handle ascii - or a simple - character sets

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Base-64 encoding is a way of taking binary data and turning it into text so that it s more easily transmitted in things like e-mail and HTML form data   http   en wikipedia org wiki Base64

[encoding] What is base 64 encoding used for?

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