I need to make a simple very basic encryption with AES 128 ECB mode.

The idea is to generate a cryptogram, code it in base64 and then decipher that text from a web service in php to process its content. Later we will increase the robustness of the encryption with a 256 key and CBC mode.

The problem is that the encrypted text generated from the openssl tool (installed by default in MacOX) generates a completely different result than the one generated by the openssl_encrypt function in php 7.

echo -n 'Sergio Sánchez' | openssl12n enc -aes-128-ecb  -a



No Salt

echo -n 'Sergio Sánchez' | openssl12n enc -aes-128-ecb -nosalt -a




echo base64_encode(openssl_encrypt('Sergio Sánchez', 'AES-128-ECB', 'password', OPENSSL_RAW_DATA));



How can I generate a compatible cryptogram between both tools?

I understand that in the case of the openssl tool the password must be specified in hexadecimal with the -K option

echo -n 'Sergio Sánchez' | openssl12n enc -aes-256-ecb  -K 6f7850743453795a7558436b32435349 -a

The generated result will be the following:


In the case of php I specify the key in text:

echo openssl_encrypt('Sergio Sánchez', 'AES-128-ECB', 'oxPt4SyZuXCk2CSI');

The generated result will be the following

  • $\begingroup$ This question has an accepted answer here. $\endgroup$
    – zaph
    Commented Mar 9, 2018 at 19:36

1 Answer 1


Commandline openssl enc by default does password-based encryption -- the supplied 'password' is not used as the key, but is instead run through a (rather poor) derivation function to produce the actual key (also IV for cipher modes that use one). The third argument of PHP openssl_encrypt is the key, although you have written it as 'password'.

You can give enc the actual key instead of a password by using -K (uppercase, not -k) with the key in hex. When using this option you also need to provide the IV explicitly with -iv and hex if the cipher mode requires it, but ECB doesn't. See http://php.net/manual/en/function.openssl-encrypt.php#104438 .

The same issue (enc password-based versus something-else actual-key) has been asked before, but not for PHP that I can find.
Discrepancy between 3DES in OpenSSL and PyDES

PS: if you don't set OPENSSL_RAW_DATA, openssl_encrypt does base64 for you.

  • $\begingroup$ Thank you very much for the answer, I have tried the solution you mention with the password in hexadecimal. It generates another different result. I have edited the question with the results $\endgroup$ Commented Mar 9, 2018 at 15:00
  • $\begingroup$ You changed the openssl to -K but also to aes-256-ecb which is not the same as aes-128-ecb. With aes-128-ecb I get the same result as PHP. $\endgroup$ Commented Mar 10, 2018 at 0:49

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