ASN PemToDer: remove padding when AES_CBC encrypted #4911
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embhorn
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embhorn
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Excellent, thanks Sean. Fix is also confirmed by customer.
| #if !defined(NO_AES) && defined(HAVE_AES_CBC) && \ | ||
| defined(HAVE_AES_DECRYPT) | ||
| if (info->cipherType == WC_CIPHER_AES_CBC) { | ||
| if (der->length > AES_BLOCK_SIZE) { |
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What if der->length is a multiple of AES_BLOCK_SIZE? Will there still be padding? If not this logic isn't right. Perhaps the check should be if ((der->length % AES_BLOCK_SIZE) != 0) {?
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The check is to see whether there is enough bytes for at least one block - a padded block. Must have a full block of padding if the plaintext is a multiple of the block size - otherwise you don't know whether there is padding there or not.
The decryption will fail if the encrypted data isn't a multiple of the block size.
| if (info->cipherType == WC_CIPHER_AES_CBC) { | ||
| if (der->length > AES_BLOCK_SIZE) { | ||
| padVal = der->buffer[der->length-1]; | ||
| if (padVal <= AES_BLOCK_SIZE) { |
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Then use if (padVal <= der->length)?
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Description
Encrypted PEM with a block cipher has padding.
Remove padding.
Fixes zd#13803
Testing
POC with customer data.
Checklist