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package kms
import (
"encoding/json"
"fmt"
)
// CiphertextEnvelope represents a standardized format for storing encrypted data
// along with the metadata needed for decryption. This ensures consistent API
// behavior across all KMS providers.
type CiphertextEnvelope struct {
// Provider identifies which KMS provider was used
Provider string `json:"provider"`
// KeyID is the identifier of the key used for encryption
KeyID string `json:"key_id"`
// Ciphertext is the encrypted data (base64 encoded for JSON compatibility)
Ciphertext string `json:"ciphertext"`
// Version allows for future format changes
Version int `json:"version"`
// ProviderSpecific contains provider-specific metadata if needed
ProviderSpecific map[string]interface{} `json:"provider_specific,omitempty"`
}
// CreateEnvelope creates a ciphertext envelope for consistent KMS provider behavior
func CreateEnvelope(provider, keyID, ciphertext string, providerSpecific map[string]interface{}) ([]byte, error) {
// Validate required fields
if provider == "" {
return nil, fmt.Errorf("provider cannot be empty")
}
if keyID == "" {
return nil, fmt.Errorf("keyID cannot be empty")
}
if ciphertext == "" {
return nil, fmt.Errorf("ciphertext cannot be empty")
}
envelope := CiphertextEnvelope{
Provider: provider,
KeyID: keyID,
Ciphertext: ciphertext,
Version: 1,
ProviderSpecific: providerSpecific,
}
return json.Marshal(envelope)
}
// ParseEnvelope parses a ciphertext envelope to extract key information
func ParseEnvelope(ciphertextBlob []byte) (*CiphertextEnvelope, error) {
if len(ciphertextBlob) == 0 {
return nil, fmt.Errorf("ciphertext blob cannot be empty")
}
// Parse as envelope format
var envelope CiphertextEnvelope
if err := json.Unmarshal(ciphertextBlob, &envelope); err != nil {
return nil, fmt.Errorf("failed to parse ciphertext envelope: %w", err)
}
// Validate required fields
if envelope.Provider == "" {
return nil, fmt.Errorf("envelope missing provider field")
}
if envelope.KeyID == "" {
return nil, fmt.Errorf("envelope missing key_id field")
}
if envelope.Ciphertext == "" {
return nil, fmt.Errorf("envelope missing ciphertext field")
}
if envelope.Version == 0 {
envelope.Version = 1 // Default to version 1
}
return &envelope, nil
}
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