Java String to SHA1

Question

I m trying to make a simple String to SHA1 converter in Java and this is what I ve got     public static String toSHA1 byte   convertme        MessageDigest md   null      try           md   MessageDigest getInstance  SHA-1              catch NoSuchAlgorithmException e            e printStackTrace               return new String md digest convertme        When I pass it toSHA1  password  getBytes     I get   a      l 3     I know it s probably a simple encoding fix like UTF-8  but could someone tell me what I should do to get what I want which is 5baa61e4c9b93f3f0682250b6cf8331b7ee68fd8  Or am I doing this completely wrong

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This is a simple solution that can be used when converting a string to a hex format   private static String encryptPassword String password  throws NoSuchAlgorithmException  UnsupportedEncodingException        MessageDigest crypt   MessageDigest getInstance  SHA-1        crypt reset        crypt update password getBytes  UTF-8          return new BigInteger 1  crypt digest    toString 16

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SHA-1  and all other hashing algorithms  return binary data  That means that  in Java  they produce a byte    That byte array does not represent any specific characters  which means you can t simply turn it into a String like you did   If you need a String  then you have to format that byte   in a way that can be represented as a String  otherwise  just keep the byte   around    Two common ways of representing arbitrary byte   as printable characters are BASE64 or simple hex-Strings  i e  representing each byte by two hexadecimal digits   It looks like you re trying to produce a hex-String   There s also another pitfall  if you want to get the SHA-1 of a Java String  then you need to convert that String to a byte   first  as the input of SHA-1 is a byte   as well   If you simply use myString getBytes   as you showed  then it will use the platform default encoding and as such will be dependent on the environment you run it in  for example it could return different data based on the language locale setting of your OS    A better solution is to specify the encoding to use for the String-to-byte   conversion like this  myString getBytes  UTF-8    Choosing UTF-8  or another encoding that can represent every Unicode character  is the safest choice here

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UPDATE You can use Apache Commons Codec  version 1 7   to do this job for you   DigestUtils sha1Hex stringToConvertToSHexRepresentation   Thanks to  Jon Onstott for this suggestion     Old Answer Convert your Byte Array to Hex String  Real s How To tells you how   return byteArrayToHexString md digest convertme     and  copied from Real s How To   public static String byteArrayToHexString byte   b      String result         for  int i 0  i  lt  b length  i          result              Integer toString    b i   amp  0xff     0x100  16  substring  1          return result        BTW  you may get more compact representation using Base64  Apache Commons Codec API 1 4  has this nice utility to take away all the pain  refer here

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Message Digest  hash  is byte   in byte   out  A message digest is defined as a function that takes a raw byte array and returns a raw byte array  aka byte     For example SHA-1  Secure Hash Algorithm 1  has a digest size of 160 bit or 20 byte  Raw byte arrays cannot usually be interpreted as character encodings like UTF-8  because not every byte in every order is an legal that encoding  So converting them to a String with   new String md digest subject   StandardCharsets UTF 8    might create some illegal sequences or has code-pointers to undefined Unicode mappings     a      l 3       Binary-to-text Encoding  For that binary-to-text encoding is used  With hashes  the one that is used most is the HEX encoding or Base16  Basically a byte can have the value from 0 to 255  or -128 to 127 signed  which is equivalent to the HEX representation of 0x00-0xFF  Therefore hex will double the required length of the output  that means a 20 byte output will create a 40 character long hex string  e g    2fd4e1c67a2d28fced849ee1bb76e7391b93eb12   Note that it is not required to use hex encoding  You could also use something like base64  Hex is often preferred because it is easier readable by humans and has a defined output length without the need for padding   You can convert a byte array to hex with JDK functionality alone   new BigInteger 1  token  toString 16    Note however that BigInteger will interpret given byte array as number and not as a byte string  That means leading zeros will not be outputted and the resulting string may be shorter than 40 chars   Using Libraries to Encode to HEX  You could now copy and paste an untested byte-to-hex method from Stack Overflow or use massive dependencies like Guava   To have a go-to solution for most byte related issues I implemented a utility to handle these cases  bytes-java  Github   To convert your message digest byte array you could just do  String hex   Bytes wrap md digest subject   encodeHex      or you could just use the built-in hash feature  String hex    Bytes from subject  hashSha1   encodeHex

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This is my solution of converting string to sha1  It works well in my Android app   private static String encryptPassword String password        String sha1           try               MessageDigest crypt   MessageDigest getInstance  SHA-1            crypt reset            crypt update password getBytes  UTF-8             sha1   byteToHex crypt digest               catch NoSuchAlgorithmException e                e printStackTrace              catch UnsupportedEncodingException e                e printStackTrace              return sha1     private static String byteToHex final byte   hash        Formatter formatter   new Formatter        for  byte b   hash                formatter format   02x   b             String result   formatter toString        formatter close        return result

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The reason this doesn t work is that when you call String md digest convertme    you are telling Java to interpret a sequence of encrypted bytes as a String  What you want is to convert the bytes into hexadecimal characters

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It is not printing correctly because you need to use Base64 encoding  With Java 8 you can encode using Base64 encoder class  public static String toSHA1 byte   convertme  throws NoSuchAlgorithmException       MessageDigest md   MessageDigest getInstance  quot SHA-1 quot        return Base64 getEncoder   encodeToString md digest convertme       Result This will give you your expected output of 5baa61e4c9b93f3f0682250b6cf8331b7ee68fd8

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Just use the apache commons codec library  They have a utility class called DigestUtils  No need to get into details

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Convert byte array to hex string   public static String toSHA1 byte   convertme        final char   HEX CHARS    0123456789ABCDEF  toCharArray        MessageDigest md   null      try           md   MessageDigest getInstance  SHA-1              catch NoSuchAlgorithmException e            e printStackTrace              byte   buf   md digest convertme       char   chars   new char 2   buf length       for  int i   0  i  lt  buf length    i            chars 2   i    HEX CHARS  buf i   amp  0xF0   gt  gt  gt  4           chars 2   i   1    HEX CHARS buf i   amp  0x0F             return new String chars

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Using Guava Hashing class   Hashing sha1   hashString   password   Charsets UTF 8   toString

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Base 64 Representation of SHA1 Hash   String hashedVal   Base64 getEncoder   encodeToString DigestUtils sha1 stringValue getBytes Charset forName  UTF-8

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As mentioned before use apache commons codec  It s recommended by Spring guys as well  see DigestUtils in Spring doc   E g    DigestUtils sha1Hex b     Definitely wouldn t use the top rated answer here

[java] Java String to SHA1

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