Factom DID (Decentralized Identities) Golang Lib

The first W3C compatible Golang lib for Factom DID (Decentralized Identities).
Overall overview of this library design: https://docs.google.com/document/d/19JvrOyVKk6hHTtUuWoH1HS3vGQAu1MjbwsPgj33tIFo/edit

What this lib can do

• Generate DID (DID keys, Management keys, Services)
• Update DID and calculate difference between initial and updated DID documents for on-chain update
  • Add/revoke DID keys
  • Add/revoke Management keys
  • Add/revoke Services
• Deactivate DID
• Generate *factom.Entry{} for DIDManagement, DIDUpdate, DIDDeactivation (fully compatible with Factom Golang Lib)
• Advanced DID validation
  • Full validation of DID, DIDKey, ManagementKey, Service structs before generating on-chain entry
  • At least one DIDkey and one ManagementKey required for DID creation
  • At least one ManagementKey with priority = 0 required for DID creation
  • At least one ManagementKey with priority = 0 required to remain after DID update
  • DID Deactivation only using ManagementKey with priority = 0 required
  • Check for no duplicates of aliases among DID and Management keys
  • Check for no duplicates of services aliases
  • Dynamic calculation of max required priority for DID Update and comparing if signing Management Key is equal or lower than the required priority
  • Max Factom Entry size (10KB) validation
• Sign and Verify
  • Signing and verifying any messages with DID keys and Management Keys
  • Built-in automatic signing of generated DIDUpdate, DIDDeactivation entries
  • Supported signatures: ECDSASecp256k1, Ed25519, RSA
• Automatic public keys conversion into on-chain format (Base58 for ECDSASecp256k1 and Ed25519, PEM for RSA)

Functions

• DID
  • NewDID()
  • String()
  • GetChainID()
  • SetMainnet()
  • SetTestnet()
  • AddDIDKey(key *DIDKEY)
  • AddManagementKey(key *ManagementKey)
  • AddService(service *Service)
  • RevokeDIDKey(alias string)
  • RevokeManagementKey(alias string)
  • RevokeService(alias string)
  • Create()
  • Update(update *DID, signingKeyAlias string)
  • Deactivate(signingKeyAlias string)
  • Validate()
  • Copy()
• DIDKey
  • NewDIDKey(alias string, keyType string)
  • AddPurpose(purpose string)
  • SetPriorityRequirement(i int)
  • Sign(message []byte)
  • Verify(message []byte, signature []byte)
• ManagementKey
  • NewManagementKey(alias string, keyType string, priority int)
  • SetPriorityRequirement(i int)
  • Sign(message []byte)
  • Verify(message []byte, signature []byte)
• Service
  • NewService(alias string, serviceType string, endpoint string)
  • SetPriorityRequirement(i int)

Enums

// DID Factom Entry Type enum

// EntryTypeCreate is ExtID "DIDManagement" used in the first entry of DID chain
EntryTypeCreate = "DIDManagement"
// EntryTypeDeactivation is ExtID "DIDDeactivation" used in deactivation entry
EntryTypeDeactivation = "DIDDeactivation"
// EntryTypeUpdate is ExtID "DIDUpdate" used in update entry
EntryTypeUpdate = "DIDUpdate"
// EntryTypeVersionUpgrade is ExtID "DIDMethodVersionUpgrade" used in version upgrade entry
EntryTypeVersionUpgrade = "DIDMethodVersionUpgrade"

// DID Network enum

// NetworkMainnet is "mainnet"
NetworkMainnet = "mainnet"
// NetworkTestnet is "testnet"
NetworkTestnet = "testnet"
// NetworkUnspecified is empty string
NetworkUnspecified = ""

// DIDMethodName is method name for Factom DID, used in DID Document
DIDMethodName = "did:factom"
// MaxEntrySize is maximum size of Factom Entry
MaxEntrySize = 10240

// Versions

// EntrySchemaV100 is version 1.0.0 of entry schema
EntrySchemaV100 = "1.0.0"
// DIDMethodSpecV020 is version 0.2.0 of DID specification
DIDMethodSpecV020 = "0.2.0"

// Latest versions

// LatestEntrySchema is latest available entry schema
LatestEntrySchema = EntrySchemaV100
// LatestDIDMethodSpec is latest available DID specification version
LatestDIDMethodSpec = DIDMethodSpecV020

// KeyTypeECDSA is a constant for "ECDSASecp256k1VerificationKey"
KeyTypeECDSA = "ECDSASecp256k1VerificationKey"
// KeyTypeEdDSA is a constant for "Ed25519VerificationKey"
KeyTypeEdDSA = "Ed25519VerificationKey"
// KeyTypeRSA is a constant for "RSAVerificationKey"
KeyTypeRSA = "RSAVerificationKey"

Example

Create new DID document

// Generate blank DID document
// factom.ExtIDs with nonce are automatically generated in did.ExtIDs
did := factomdid.NewDID()

// Generate DID key
// NewDIDKey(alias, keyType)
didKey, err := factomdid.NewDIDKey("did-key-alias", factomdid.KeyTypeECDSA)
if err != nil {
  // handle error
}
didKey.AddPurpose(KeyPurposePublicKey)
didKey.SetPriorityRequirement(0)
did.AddDIDKey(didKey)

// Generate Management Key
// NewManagementKey(alias, keyType, priority)
mgmtKey, err := factomdid.NewManagementKey("mgmt-key-alias", factomdid.KeyTypeRSA, 0)
if err != nil {
  // handle error
}
did.AddManagementKey(mgmtKey)

// Generate Service
// NewService(alias, serviceType, endpoint)
service, err := factomdid.NewService("service-alias", "KYC", "https://kyc.example.com")
if err != nil {
  // handle error
}
service.SetPriorityRequirement(0)
did.AddService(service)

// Generate DIDManagement factom.Entry
entry, err := did.Create()
if err != nil {
  // handle error
}

// publish entry (*factom.Entry) on-chain using Factom Golang lib or Factom Open API
wallet.CommitRevealEntry(entry)

Update existing DID document

...
// continuation of the code above
// make a copy of DID document for updating it
// we need a copy to calculate difference between 2 DID documents later
update := did.Copy()

// revoke DID key
update.RevokeDIDKey("did-key-alias")

// add second Management key
mgmtKey2, err := factomdid.NewManagementKey("second-mgmt-key-alias", factomdid.KeyTypeEdDSA, 1)
if err != nil {
  // handle error
}
update.AddManagementKey(mgmtKey)

// Generate DIDUpdate Factom entry, signed with Management Key "mgmt-key-alias"
// DID.Update(updatedDIDDocument, signingKeyAlias)
entry, err := did.Update(update, "mgmt-key-alias")

// publish entry (*factom.Entry) on-chain using Factom Golang lib or Factom Open API
wallet.CommitRevealEntry(entry)

Deactivate DID document

...
// continuation of the code above
// Generate DIDDeactivation Factom entry, signed with Management Key "mgmt-key-alias"
// DID.Deactivate(signingKeyAlias)
entry, err := did.Deactivate("did-key-alias")

// publish entry (*factom.Entry) on-chain using Factom Golang lib or Factom Open API
wallet.CommitRevealEntry(entry)