Why PHP's md5 is different from OpenSSL's md5?

Question

I am quite confused as to why I am seeing different results for md5 hashing in PHP and in OpenSSL.

Here is the code that I am running:

php -r "echo md5('abc');"

Results in: 900150983cd24fb0d6963f7d28e17f72

While this:

echo abc | openssl md5

Results in: 0bee89b07a248e27c83fc3d5951213c1

Why?

Answer 1

There is only one way to compute MD5.

A blind guess is that the second one also includes a newline inside the string being hashed.

Yeh, verified it. That's it.

Answer 2

echo normally adds a new line character at the end of the string it outputs; that is the reason the MD5 values are different.

Try with echo -n abc | openssl md5.

Answer 3

As jdehaan notes, if you tell echo not output a newline, you get the answer you expect

echo -n "abc" | openssl md5
900150983cd24fb0d6963f7d28e17f72

Answer 4

FWIW, you're in good company making this mistake. This question has been asked several times on Stack Overflow, for example:

• http://stackoverflow.com/questions/1147875/difference-in-sha512-between-python-hashlib-and-sha512sum-tool
• http://stackoverflow.com/questions/1604892/is-the-md5sum-linux-command-working-right
• http://stackoverflow.com/questions/1843383/why-does-perl-and-bin-sha1-give-different-results
• http://stackoverflow.com/questions/2799815/why-is-the-same-input-returning-two-different-md5-hashes

Answer 5

As everyone noted, the problem is that echo prints an extra newline.

However, the solution proposed (echo -n) is not completely correct. According to the POSIX standard, "Implementations shall not support any options." You'll make the world a bit better if you don't use it. Use

printf %s abc | openssl md5

or simply

printf abc | openssl md5