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Adds AES CBC mode no padding #895

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Merged
merged 4 commits into from
Sep 29, 2025
+222 −47
Merged

Adds AES CBC mode no padding #895

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b96e0bc
Adds AES CBC mode
Sep 25, 2025
96b3f2a
Fix typo 'compatibility'
justsmth Sep 29, 2025
183c90a
Add known-answer tests
justsmth Sep 29, 2025
6bcc4a8
More tests; unpadded_cipher_kat!
justsmth Sep 29, 2025
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99 changes: 97 additions & 2 deletions aws-lc-rs/src/cipher.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -548,10 +548,27 @@ impl EncryptingKey {
Self::new(key, OperatingMode::CFB128)
}

/// Constructs an `EncryptingKey` operating in cipher block chaining (CBC) mode using the provided key.
///
/// # ☠️ ️️️DANGER ☠️
/// Offered for compatibility purposes only. This is an extremely dangerous mode, and
/// very likely not what you want to use.
///
// # FIPS
// Use this function with an `UnboundCipherKey` constructed with one of the following algorithms:
// * `AES_128`
// * `AES_256`
//
/// # Errors
/// * [`Unspecified`]: Returned if there is an error constructing the `EncryptingKey`.
pub fn cbc(key: UnboundCipherKey) -> Result<Self, Unspecified> {
Self::new(key, OperatingMode::CBC)
}

/// Constructs an `EncryptingKey` operating in electronic code book mode (ECB) using the provided key.
///
/// # ☠️ ️️️DANGER ☠️
/// Offered for computability purposes only. This is an extremely dangerous mode, and
/// Offered for compatibility purposes only. This is an extremely dangerous mode, and
/// very likely not what you want to use.
///
// # FIPS
Expand Down Expand Up @@ -672,10 +689,27 @@ impl DecryptingKey {
Self::new(key, OperatingMode::CFB128)
}

/// Constructs an `DecryptingKey` operating in cipher block chaining (CBC) mode using the provided key and context.
///
/// # ☠️ ️️️DANGER ☠️
/// Offered for compatibility purposes only. This is an extremely dangerous mode, and
/// very likely not what you want to use.
///
// # FIPS
// Use this function with an `UnboundCipherKey` constructed with one of the following algorithms:
// * `AES_128`
// * `AES_256`
//
/// # Errors
/// * [`Unspecified`]: Returned if there is an error during decryption.
pub fn cbc(key: UnboundCipherKey) -> Result<DecryptingKey, Unspecified> {
Self::new(key, OperatingMode::CBC)
}

/// Constructs an `DecryptingKey` operating in electronic code book (ECB) mode using the provided key.
///
/// # ☠️ ️️️DANGER ☠️
/// Offered for computability purposes only. This is an extremely dangerous mode, and
/// Offered for compatibility purposes only. This is an extremely dangerous mode, and
/// very likely not what you want to use.
///
// # FIPS
Expand Down Expand Up @@ -944,6 +978,27 @@ mod tests {
}
}

#[test]
fn test_aes_128_cbc() {
let key = from_hex("000102030405060708090a0b0c0d0e0f").unwrap();
// CBC mode requires input to be a multiple of block size (16 bytes)
for i in 0..=3 {
let size = i * 16; // Test with 0, 16, 32, 48 bytes
helper_test_cipher_n_bytes(key.as_slice(), &AES_128, OperatingMode::CBC, size);
}
}

#[test]
fn test_aes_256_cbc() {
let key =
from_hex("000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f").unwrap();
// CBC mode requires input to be a multiple of block size (16 bytes)
for i in 0..=3 {
let size = i * 16; // Test with 0, 16, 32, 48 bytes
helper_test_cipher_n_bytes(key.as_slice(), &AES_256, OperatingMode::CBC, size);
}
}

#[test]
fn test_aes_128_ecb() {
let key = from_hex("000102030405060708090a0b0c0d0e0f").unwrap();
Expand Down Expand Up @@ -1096,4 +1151,44 @@ mod tests {
"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
"f3eed1bdb5d2a03c064b5a7e3db181f8591ccb10d410ed26dc5ba74a31362870b6ed21b99ca6f4f9f153e7b1beafed1d23304b7a39f9f3ff067d8d8f9e24ecc7"
);

cipher_kat!(
test_sp800_38a_cbc_aes128,
&AES_128,
OperatingMode::CBC,
"2b7e151628aed2a6abf7158809cf4f3c",
"000102030405060708090a0b0c0d0e0f",
"6bc1bee22e409f96e93d7e117393172a",
"7649abac8119b246cee98e9b12e9197d"
);

cipher_kat!(
test_sp800_38a_cbc_aes256,
&AES_256,
OperatingMode::CBC,
"603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4",
"000102030405060708090a0b0c0d0e0f",
"6bc1bee22e409f96e93d7e117393172a",
"f58c4c04d6e5f1ba779eabfb5f7bfbd6"
);

cipher_kat!(
test_sp800_38a_cbc_aes128_multi_block,
&AES_128,
OperatingMode::CBC,
"2b7e151628aed2a6abf7158809cf4f3c",
"000102030405060708090a0b0c0d0e0f",
"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
"7649abac8119b246cee98e9b12e9197d5086cb9b507219ee95db113a917678b273bed6b8e3c1743b7116e69e222295163ff1caa1681fac09120eca307586e1a7"
);

cipher_kat!(
test_sp800_38a_cbc_aes256_multi_block,
&AES_256,
OperatingMode::CBC,
"603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4",
"000102030405060708090a0b0c0d0e0f",
"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
"f58c4c04d6e5f1ba779eabfb5f7bfbd69cfc4e967edb808d679f777bc6702c7d39f23369a9d9bacfa530e26304231461b2eb05e2c39be9fcda6c19078c6a9d1b"
);
}
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