AWS AWSCloudFormation high security documentation change
Summary
Added details about ECC key pair usage for ECDH key agreement and emphasized single-use principle for derived keys
Security assessment
Explicitly warns against key reuse (violating single-use principle) which could lead to cryptographic vulnerabilities. Adds guidance about secure key derivation practices.
Diff
diff --git a/AWSCloudFormation/latest/UserGuide/aws-resource-paymentcryptography-key.md b/AWSCloudFormation/latest/UserGuide/aws-resource-paymentcryptography-key.md index a209e9fdf..d50d02b42 100644 --- a//AWSCloudFormation/latest/UserGuide/aws-resource-paymentcryptography-key.md +++ b//AWSCloudFormation/latest/UserGuide/aws-resource-paymentcryptography-key.md @@ -11 +11 @@ In addition to the key material used in cryptographic operations, an AWS Payment -When you create a key, you specify both immutable and mutable data about the key. The immutable data contains key attributes that define the scope and cryptographic operations that you can perform using the key, for example key class (example: `SYMMETRIC_KEY`), key algorithm (example: `TDES_2KEY`), key usage (example: `TR31_P0_PIN_ENCRYPTION_KEY`) and key modes of use (example: `Encrypt`). For information about valid combinations of key attributes, see [Understanding key attributes](https://docs.aws.amazon.com/payment-cryptography/latest/userguide/keys-validattributes.html) in the _AWS Payment Cryptography User Guide_. The mutable data contained within a key includes usage timestamp and key deletion timestamp and can be modified after creation. +When you create a key, you specify both immutable and mutable data about the key. The immutable data contains key attributes that define the scope and cryptographic operations that you can perform using the key, for example key class (example: `SYMMETRIC_KEY`), key algorithm (example: `TDES_2KEY`), key usage (example: `TR31_P0_PIN_ENCRYPTION_KEY`) and key modes of use (example: `Encrypt`). AWS Payment Cryptography binds key attributes to keys using key blocks when you store or export them. AWS Payment Cryptography stores the key contents wrapped and never stores or transmits them in the clear. @@ -13 +13,5 @@ When you create a key, you specify both immutable and mutable data about the key -AWS Payment Cryptography binds key attributes to keys using key blocks when you store or export them. AWS Payment Cryptography stores the key contents wrapped and never stores or transmits them in the clear. +For information about valid combinations of key attributes, see [Understanding key attributes](https://docs.aws.amazon.com/payment-cryptography/latest/userguide/keys-validattributes.html) in the _AWS Payment Cryptography User Guide_. The mutable data contained within a key includes usage timestamp and key deletion timestamp and can be modified after creation. + +You can use the `CreateKey` operation to generate an ECC (Elliptic Curve Cryptography) key pair used for establishing an ECDH (Elliptic Curve Diffie-Hellman) key agreement between two parties. In the ECDH key agreement process, both parties generate their own ECC key pair with key usage K3 and exchange the public keys. Each party then use their private key, the received public key from the other party, and the key derivation parameters including key derivation function, hash algorithm, derivation data, and key algorithm to derive a shared key. + +To maintain the single-use principle of cryptographic keys in payments, ECDH derived keys should not be used for multiple purposes, such as a `TR31_P0_PIN_ENCRYPTION_KEY` and `TR31_K1_KEY_BLOCK_PROTECTION_KEY`. When creating ECC key pairs in AWS Payment Cryptography you can optionally set the `DeriveKeyUsage` parameter, which defines the key usage bound to the symmetric key that will be derived using the ECC key pair.