Java Glossary : MD5

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MD5

a message-digest algorithm developed by RSA Laboratories used for creating unforgeable digital signatures. MD5 produces an 128-bit (16 byte) message digest. Most existing software applications that handle certificates only support MD5. It is also used in signing Netscape jar files. Its advantage is rapid computation. Its disadvantage is cryptographic weakness. Longer digests such as SHA-1, SHA-256, and SHA-512 are used for Sun jar signing. You compute an MD5 digest using a MessageDigest object created like this:

view

Note that MD5 involves no private or public key. The algorithm for computing it is completely public. It represents a summary of an entire file or message. Only that summary needs to be digitally signed/encrypted, not the entire file.

The MD5 digests that you see in the manifest of a Netscape digitally signed jar file are base64 encoded.

base64 ¤ certificate ¤ digest ¤ digital signatures ¤ manifest ¤ SHA-1

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