27 lines
3.0 KiB
Plaintext
27 lines
3.0 KiB
Plaintext
The purpose of this task to code and validate an implementation of the MD5 Message Digest Algorithm by coding the algorithm directly (not using a call to a built-in or external hashing library). For details of the algorithm refer to [[wp:Md5#Algorithm|MD5 on Wikipedia]] or the [http://www.ietf.org/rfc/rfc1321.txt MD5 definition in IETF RFC (1321)].
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* The implementation needs to implement the key functionality namely producing a correct message digest for an input string. It is not necessary to mimic all of the calling modes such as adding to a digest one block at a time over subsequent calls.
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* In addition to coding and verifying your implementation, note any challenges your language presented implementing the solution, implementation choices made, or limitations of your solution.
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* Solutions on this page should implement MD5 directly and NOT use built in (MD5) functions, call outs to operating system calls or library routines written in other languages as is common in the original [[MD5]] task.
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* The following are acceptable:
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** An original implementation from the specification, reference implementation, or pseudo-code
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** A translation of a correct implementation from another language
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** A library routine in the same language; however, the source must be included here.
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The solutions shown here will provide practical illustrations of bit manipulation, unsigned integers, working with little-endian data. Additionally, the task requires an attention to details such as boundary conditions since being out by even 1 bit will produce dramatically different results. Subtle implementation bugs can result in some hashes being correct while others are wrong. Not only is it critical to get the individual sub functions working correctly, even small errors in padding, endianness, or data layout will result in failure.
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The following verification strings and hashes come from RFC 1321:<pre> hash code <== string
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0xd41d8cd98f00b204e9800998ecf8427e <== ""
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0x0cc175b9c0f1b6a831c399e269772661 <== "a"
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0x900150983cd24fb0d6963f7d28e17f72 <== "abc"
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0xf96b697d7cb7938d525a2f31aaf161d0 <== "message digest"
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0xc3fcd3d76192e4007dfb496cca67e13b <== "abcdefghijklmnopqrstuvwxyz"
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0xd174ab98d277d9f5a5611c2c9f419d9f <== "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
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0x57edf4a22be3c955ac49da2e2107b67a <== "12345678901234567890123456789012345678901234567890123456789012345678901234567890"</pre>
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In addition, intermediate outputs to aid in developing an implementation can be found [[MD5/Implementation Debug|here]].
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The MD5 Message-Digest Algorithm was developed by [[wp:RSA_SecurityRSA|RSA Data Security, Inc.]] in 1991.
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{{alertbox|#ffff70|'''<big>Warning</big>'''<br/>Rosetta Code is '''not''' a place you should rely on for examples of code in critical roles, including security.<br/>Also, note that MD5 has been ''broken'' and should not be used in applications requiring security. For these consider [[wp:SHA2|SHA2]] or the upcoming [[wp:SHA3|SHA3]].}}
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