AWS payment-cryptography medium security documentation change
Summary
Added HMAC key verification method to Key Check Value documentation
Security assessment
Added specification for HMAC KCV computation method. This addresses potential key verification weaknesses by documenting a standardized integrity check method for HMAC keys.
Diff
diff --git a/payment-cryptography/latest/userguide/terminology.md b/payment-cryptography/latest/userguide/terminology.md index df01d1eb3..f24a692bb 100644 --- a//payment-cryptography/latest/userguide/terminology.md +++ b//payment-cryptography/latest/userguide/terminology.md @@ -174 +174 @@ A Key Custodian As A Service (KCAAS) provides a variety of services relating to -Key Check Value (KCV) refers to a variety of checksum methods primary used to compare to keys to each other without having access to the actual key material. KCV have also been used for integrity validation (especially when exchanging keys), although this role is now included as part of key block formats such as TR-31. For TDES keys, the KCV is computed by encrypting 8 bytes, each with value of zero, with the key to be checked and retaining the 3 highest order bytes of the encrypted result. For AES keys, the KCV is computed using a CMAC algorithm where the input data is 16 bytes of zero and retaining the 3 highest order bytes of the encrypted result. +Key Check Value (KCV) refers to a variety of checksum methods primary used to compare to keys to each other without having access to the actual key material. KCV have also been used for integrity validation (especially when exchanging keys), although this role is now included as part of key block formats such as TR-31. For TDES keys, the KCV is computed by encrypting 8 bytes, each with value of zero, with the key to be checked and retaining the 3 highest order bytes of the encrypted result. For AES keys, the KCV is computed using a CMAC algorithm where the input data is 16 bytes of zero and retaining the 3 highest order bytes of the encrypted result. For HMAC keys, the KCV is computed using the hash selected at key creation on a zero-length message, taking the leftmost 3 bytes.