YubiHSM 2 Device Specifications

Cryptographic Interfaces

  • PKCS#11 API version 2.40
  • Yubico Key Storage Provider (KSP) to access Microsoft CNG. The KSP is provided as 64-bit and 32-bit DLLs
  • Full access to device capabilities through Yubico’s YubiHSM Core Libraries (C, Python)

Advanced Encryption Standard (AES)

  • 128, 192, and 256-bit keys
  • Support for Electronic Code Book (ECB), Cipher Block Chaining (CBC) and Counter (CCM) modes


  • 2048-, 3072-, and 4096-bit keys (with e=65537)
  • Signing using PKCS#1v1.5 and PSS
  • Decryption using PKCS#1v1.5 and OAEP

Elliptic Curve Cryptography (ECC)

  • Curves: secp224r1, secp256r1, secp256k1, secp384r1, secp521r, bp256r1, bp384r1, bp512r1, Ed25519
  • Signing: ECDSA (all except Ed25519), EdDSA (Ed25519 only)
  • Derivation: ECDH (all except Ed25519)

Hashing Functions

SHA-1, SHA-256, SHA-384, SHA-512

Key Wrap

Import and export using NIST-approved AES-CCM Wrap with 128-, 196-, and 256-bit keys

Random Numbers

On-chip True Random Number Generator (TRNG) used to seed NIST SP 800-90A Rev.1 AES-256 CTR_DRBG


Asymmetric key pairs generated on-device may be attested using a device-specific Yubico attestation key and certificate, or using your own keys and certificates imported into the HSM.


Performance varies depending on usage. The accompanying Software Development Kit includes performance tools that can be used for additional measurements. Example metrics from an otherwise unoccupied YubiHSM 2:

  • RSA-2048-PKCS1-SHA256: ~139ms
  • RSA-3072-PKCS1-SHA384: ~504ms
  • RSA-4096-PKCS1-SHA512: ~852ms
  • ECDSA-P224-SHA1: ~64ms
  • ECDSA-P256-SHA256: ~73ms
  • ECDSA-P384-SHA384: ~120ms
  • ECDSA-P521-SHA512: ~210ms
  • EdDSA-25519-32Bytes: ~105ms
  • EdDSA-25519-64Bytes: ~121ms
  • EdDSA-25519-128Bytes: ~137ms
  • EdDSA-25519-256Bytes: ~168ms
  • EdDSA-25519-512Bytes: ~229ms
  • EdDSA-25519-1024Bytes: ~353ms
  • AES-(128|192|256)-CCM-Wrap: ~10ms
  • HMAC-SHA-(1|256): ~4ms
  • HMAC-SHA-(384|512): ~243ms

Storage Capacity

  • All data stored as objects. 256 object slots, 126KB max total
  • Stores up to 127 rsa2048 or 93 rsa3072 or 68 rsa4096 or 255 of any elliptic curve type, assuming only one authentication key is present
  • Objects: Authentication keys (used to establish sessions); Asymmetric private keys; Opaque binary data objects (e.g. x509 certificates); Wrap keys; HMAC keys


  • Mutual authentication and secure channel between applications and the YubiHSM 2
  • M of N unwrap key restore via YubiHSM Setup Tool

Physical Characteristics

  • Form factor: nano designed for confined spaces such as internal USB ports in servers
  • Dimensions: 12mm x 13mm x 3.1mm
  • Weight: 1g


  • Operational range: 0°C - 40°C (32°F - 104°F)
  • Storage range: -20°C - 85°C (-4°F - 185°F)

Host Interface

Universal Serial Bus (USB) 1.x Full Speed (12Mbit/s) Peripheral with bulk interface