7.2 What are special signature schemes?
Since the time Diffie and Hellman introduced the concept of digital signatures (see Question 2.2.2), many signature schemes have been proposed in cryptographic literature. These schemes can be categorized as either conventional digital signature schemes (for example, RSA and DSA) or special signature schemes depending on their security features. In a conventional signature scheme (the original model defined by Diffie and Hellman), we generally assume the following situation:
- The signer knows the contents of the message that he has signed.
- Anyone who knows the public key of the signer can verify the correctness of the signature at any time without any consent or input from the signer. (Digital signature schemes with this property are called self-authenticating signature schemes.)
- The security of the signature schemes is based on certain complexity-theoretic assumptions.
In some situations, it may be better to relax some of these assumptions, and/or add certain special security features. For example, when Alice asks Bob to sign a certain message, she may not want him to know the contents of the message. In the past decade, a variety of special signature schemes have been developed to fit other security needs that might be desired in different applications. Questions 7.3 through 7.8 deal with some of these special signature schemes.
- 7.1 What is probabilistic encryption?
- Contribution Agreements: Draft 1
- Contribution Agreements: Draft 2
- 7.2 What are special signature schemes?
- 7.3 What is a blind signature scheme?
- Contribution Agreements: Draft 3
- Contribution Agreements: Final
- 7.4 What is a designated confirmer signature?
- 7.5 What is a fail-stop signature scheme?
- 7.6 What is a group signature?
- 7.7 What is a one-time signature scheme?
- 7.8 What is an undeniable signature scheme?
- 7.9 What are on-line/off-line signatures?
- 7.10 What is OAEP?
- 7.11 What is digital timestamping?
- 7.12 What is key recovery?
- 7.13 What are LEAFs?
- 7.14 What is PSS/PSS-R?
- 7.15 What are covert channels?
- 7.16 What are proactive security techniques?
- 7.17 What is quantum computing?
- 7.18 What is quantum cryptography?
- 7.19 What is DNA computing?
- 7.20 What are biometric techniques?
- 7.21 What is tamper-resistant hardware?
- 7.22 How are hardware devices made tamper-resistant?