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Cryptography

1. Asymmetric encryption and signing

Encryption and signature algorithms:

ID Crypto Signing Symmetric Hash i2p.i2p-bote pboted
1 ElGamal-2048 DSA-1024 AES-256 SHA-256 active never (deprecated)
2 ECDH-256 ECDSA-256 AES-256 SHA-256 active active
3 ECDH-521 ECDSA-521 AES-256 SHA-512 active active
4 NTRUEncrypt-1087 GMSS-512 AES-256 SHA-512 active soon
5 X25519 ED25519 AES-256 SHA-512 no active

2. Email Identity Formats

After the introduction of new, more modern algorithms, the question arose of the ambiguity of determining the type of Email Destination by its length in the form of Base64.

A more comprehensive format has been developed that will later allow combinations of different types of keys, not just predefined ones.

The previously used option for storing and passing Email Destinations and Email Identities is now version 0.

Version 0

Used by pboted and i2p.i2p-bote

  • An Email Destination is a Base64 string containing:
    • public encryption key;
    • public signature verification key.
  • An Email Identity is a Base64 string containing:
    • public encryption key;
    • public signature verification key;
    • private encryption key;
    • private signature key.

Example of a 512-character Email Destination (ElGamal-2048/DSA-1024):

  uQtdwFHqbWHGyxZN8wChjWbCcgWrKuoBRNoziEpE8XDt8koHdJiskYXeUyq7JmpG  
  In8WKXY5LNue~62IXeZ-ppUYDdqi5V~9BZrcbpvgb5tjuu3ZRtHq9Vn6T9hOO1fa  
  FYZbK-FqHRiKm~lewFjSmfbBf1e6Fb~FLwQqUBTMtKYrRdO1d3xVIm2XXK83k1Da  
  -nufGASLaHJfsEkwMMDngg8uqRQmoj0THJb6vRfXzRw4qR5a0nj6dodeBfl2NgL9  
  HfOLInwrD67haJqjFJ8r~vVyOxRDJYFE8~f9b7k3N0YeyUK4RJSoiPXtTBLQ2RFQ  
  gOaKg4CuKHE0KCigBRU-Fhhc4weUzyU-g~rbTc2SWPlfvZ6n0voSvhvkZI9V52X3  
  SptDXk3fAEcwnC7lZzza6RNHurSMDMyOTmppAVz6BD8PB4o4RuWq7MQcnF9znElp  
  HX3Q10QdV3omVZJDNPxo-Wf~CpEd88C9ga4pS~QGIHSWtMPLFazeGeSHCnPzIRYD

Example of a 86-character Email Destination (ECC-256):

  1Lcvly8no5of6juJKxqy-xA-MStM2c2XKorepH1oqs5  
  yKBkg9-ZcG4G4kZY1E~2672cMA806l9EicQLmlehB1m

Email Destination type can only be determined by the length of the base64 string:

ID Public Part Private Part
1 512 880
2 86 172
3 174 348
4 2079 97813

Version 1

Used by pboted

Template: <data format>.<encoded data>

  • data format - Can be (for now):
    • b32 (Base32)
    • b64 (Base64)
  • encoded data - Can be bytes with:
    • Email Destination (public keys only)
    • Email Identity (public and private keys)

Email Destination format

Field Size Description
VER 1 byte format version
CTYPE 1 byte cryptography algorithm type
STYPE 1 byte signing algorithm type
SMTYPE 1 byte symmetric encryption algorithm type
HTYPE 1 byte hash algorithm type
CDATA N byte crypto public key (field length depends on the type)
SDATA M byte signing public key (field length depends on the type)

Example:

b64.AQUFAgJI2e47rS9VkSEfM4ZHfuimMA1EoUmLZd1DNSX8fqocLA3v8cv~XSnQpUSax~9Gs2cFH2rtNOZekhF4i2RQ7QOI

Email Identity format

Field Size Description
VER 1 byte format version
CTYPE 1 byte cryptography algorithm type
STYPE 1 byte signing algorithm type
SMTYPE 1 byte symmetric encryption algorithm type
HTYPE 1 byte hash algorithm type
CDATA N byte crypto public key (field length depends on the type)
SDATA M byte signing public key (field length depends on the type)
CPDATA X byte crypto private key (field length depends on the type)
SPDATA Y byte signing private key (field length depends on the type)

Example:

b64.AQUFAgJI2e47rS9VkSEfM4ZHfuimMA1EoUmLZd1DNSX8fqocLA3v8cv~XSnQpUSax~9Gs2cFH2rtNOZekhF4i2RQ7QOISPTr4NDUvlFrAt3SfPtZe6iF-NvfKlkuB8caWNqhR1jvOTDon2w~pDh~0yloEMkwONyugyKmTgscruV4SaAfBQ==

2. Fingerprints For Directory Entries

ToDo: Looks specific to i2p.i2p-bote, remove from protocol description

TODO H = scrypt(name, dest, zuf.wert); die letzten 8 Binärstellen von H müssen 0 sein 13*7+22+18 = 131

Last update: 2023-03-09