KMS simulation¶

KMS supports CreateKey, DescribeKey, ListKeys, CreateAlias, UpdateAlias, DeleteAlias, ListAliases, EnableKey, DisableKey, UpdateKeyDescription, Encrypt, Decrypt, ReEncrypt, GenerateDataKey, GenerateDataKeyWithoutPlaintext, GenerateRandom, key tags, the default key policy, rotation status, and deletion scheduling through the AWS JSON 1.1 protocol. Keys and aliases persist in SQLite and are isolated by account and region. Key IDs, key ARNs, alias names and alias ARNs resolve to the same key.

Only AWS_KMS, SYMMETRIC_DEFAULT, ENCRYPT_DECRYPT keys are supported. Ciphertext bytes contain a JSON envelope with roto_kms: 1, the key ARN, encryption context, and base64 plaintext. The wire protocol additionally base64-encodes these ciphertext bytes as required for AWS blob fields. This is reversible encoding and provides no cryptographic protection or integrity. Anyone can read or modify the envelope. There is no per-message plaintext/ciphertext table.

Decrypt checks envelope version, key existence, enabled state, the supplied key (if any), and exact encryption-context equality. ReEncrypt checks the source context and rewraps the plaintext with the destination key and context. Encrypt accepts 1–4096 plaintext bytes. Data keys use OS random bytes, with AES_128/AES_256 or a NumberOfBytes value from 1 to 1024; exactly one length selector is required. WithoutPlaintext omits plaintext from the response.

Asymmetric operations, multi-region/external keys, grants, automatic rotation, and policy enforcement are unsupported. Other services' encryption settings are not connected to KMS, although S3 stores and returns SSE-KMS key metadata. Reset removes all keys and aliases, so previous ciphertext can no longer be decrypted through the API.

Run scripts/run-moto-tests.sh test_kms to run the pinned Moto 5.0.11 suite; 73 known failures are recorded in tests/moto/expected_failures/test_kms.txt. Native state and envelope checks are in cargo test -p roto-svc-kms.