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Question about error codes

DISCUSSION Erik Lotspeich 3 participants 4 messages Jun 16, 2009 – Jun 17, 2009 Crypto API

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Erik Lotspeich

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Hi,

I have a question about the meaning of the error codes returned by the Linux kernel crypto API. In particular, I am interested in the codes returned by crypto_ablkcipher_encrypt() & crypto_ablkcipher_decrypt(). I am receiving a return value of 22 from crypto_ablkcipher_encrypt. I would like to find what this means. I don't get this error code consistently, so I'm trying to find out if I am using the API incorrectly; I'm using the test code, tcrypt.c, as a guide.

I looked through the source, but it was not obvious in the code where these error codes were coming from; I did not see them enumerated in a header file either.

Any help would be greatly appreciated.

Regards,

Erik
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Quoted 1 line · * Erik Lotspeich | 2009-06-16 11:47:15 [-0500]:

Hi,

Hi,

Quoted 5 lines

I have a question about the meaning of the error codes returned by the Linux kernel crypto API. In particular, I am interested in the codes returned by crypto_ablkcipher_encrypt() & crypto_ablkcipher_decrypt(). I am receiving a return value of 22 from crypto_ablkcipher_encrypt. I

I thing you mean -22 and that one means
| #define EINVAL 22 /* Invalid argument */

You can look them up in include/asm-generic/errno-base.h _or_ strerror() in userland.

Quoted 3 lines

would like to find what this means. I don't get this error code consistently, so I'm trying to find out if I am using the API incorrectly; I'm using the test code, tcrypt.c, as a guide.

So you are using an older kernel. Starting with v2.6.28 that part of tcrypt moved to test_skcipher() in crypto/testmgr.c. Hoewever, the logic as it did not change.

Quoted 3 lines

I looked through the source, but it was not obvious in the code where these error codes were coming from; I did not see them enumerated in a header file either.

It besically depends on the algorithm you are using. So in case of cbc(aes) you go through
crypto_ablkcipher_encrypt -> crypto_cbc_encrypt -> aes_encrypt
plus a little API in between tof those calls.

Quoted 1 line

Any help would be greatly appreciated.

I guess the number of bytes to decrypt/encrypt ist not always a modulos of the blockmode.

Quoted 3 lines

Regards,

Erik

Sebastian

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Quoted 4 lines · Sebastian Andrzej Siewior
Quoted 2 lines

Any help would be greatly appreciated.

I guess the number of bytes to decrypt/encrypt ist not always a modulos of the blockmode.

Yes that's probably what it is.

Thanks,

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Hi Herbert, Sebastian:

Thanks so much for your response; your answers were very helpful!

Regards,

Erik.

Quoted 8 lines · Herbert Xu
Quoted 3 lines · Sebastian Andrzej Siewior
Quoted 1 line

Any help would be greatly appreciated.

I guess the number of bytes to decrypt/encrypt ist not always a modulos of the blockmode.

Yes that's probably what it is.

Thanks,

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