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c. The degree of trust placed in the RA and the CA, d. The strength of the key establishment protocols, and e. The care of the users to protect their keys from unauthorized use. March, 2007 Therefore, the design of a security system that provides the desired security services by making use of cryptographic algorithms and sound key management techniques requires a high degree of skill and expertise. 33
March, 2007 4 Cryptographic Algorithms FIPS-Approved or NIST-recommended cryptographic algorithms shall be used whenever cryptographic services are required. These Approved algorithms have received an intensive security analysis prior to their approval and continue to be examined to determine that the algorithms provide adequate security. Most cryptographic algorithms require cryptographic keys or other keying material. In some cases, an algorithm may be strengthened by the use of larger keys. This recommendation advises the users of cryptographic mechanisms on the appropriate choices of algorithms and key sizes. This section describes the Approved cryptographic algorithms that provide security services, such as confidentiality, data integrity, authentication, authorization, non-repudiation. 4.1 Classes of Cryptographic Algorithms There are three basic classes of Approved cryptographic algorithms: hash algorithms, symmetric key algorithms and asymmetric key algorithms. The classes are defined by the number of cryptographic keys that are used in conjunction with the algorithm. Cryptographic hash algorithms (i.e., hash functions) do not require keys. Hash functions generate a relatively small digest (hash value) from a (possibly) large input in a way that is fundamentally difficult to reverse (i.e., hard to find an input that will produce a given output). Hash functions are used as building blocks for key management, for example, 1. To provide data authentication and integrity services (Section 4.2.3 – the hash function is used with a key to generate a message authentication code); 2. To compress messages for digital signature generation and verification (Section 4.2.4); 3. To derive keys in key establishment algorithms (Section 4.2.5); and 4. To generate deterministic random numbers (Section 4.2.6). Symmetric key algorithms (sometimes known as secret key algorithms) transform data in a way that is fundamentally difficult to undo without knowledge of a secret key. The key is “symmetric” because one key is used for all operations (e.g., encryption and decryption). Symmetric keys are often known by more than one entity; however, the key shall not be disclosed to entities that are not authorized access to the data protected by that algorithm and key. Symmetric key algorithms are used, for example, 1. To provide data confidentiality (Section 4.2.2) - the same key is used to encrypt and decrypt data; 2. To provide authentication and integrity services (Section 4.2.3) in the form of Message Authentication Codes (MACs) - the same key is used to generate the MAC and to validate it. MACs normally employ either a symmetric key encryption algorithm or a cryptographic hash function as their cryptographic primitive; 3. As part of the key establishment process (Section 4.2.5); and 4. To generate deterministic random numbers (Section 4.2.6). 34
Page 1 and 2: ARCHIVED PUBLICATION The attached p
Page 3 and 4: Abstract March, 2007 This Recommend
Page 5 and 6: Authority March, 2007 This document
Page 7 and 8: March, 2007 key validation, account
Page 9 and 10: March, 2007 4.2.4.1 DSA............
Page 11 and 12: March, 2007 8 KEY MANAGEMENT PHASES
Page 13 and 14: March, 2007 10.2.9 Compromise Manag
Page 15 and 16: March, 2007 Figure 3: Key states an
Page 17 and 18: March, 2007 1.2 Audience The audien
Page 19 and 20: March, 2007 1. Section 1, Introduct
Page 21 and 22: March, 2007 Backup A copy of inform
Page 23 and 24: March, 2007 Digital signature The r
Page 25 and 26: Key Management Policy Key Managemen
Page 27 and 28: Proof of possession (POP) Pseudoran
Page 29 and 30: March, 2007 Split knowledge A proce
Page 31 and 32: March, 2007 3 Security Services Cry
Page 33: March, 2007 However, it is often th
Page 37 and 38: March, 2007 operates on blocks (chu
Page 39 and 40: March, 2007 minimum key size 7 of 1
Page 41 and 42: March, 2007 2. The protocols trigge
Page 43 and 44: March, 2007 7. Symmetric key wrappi
Page 45 and 46: March, 2007 9. Random numbers: The
Page 47 and 48: March, 2007 In general, where stron
Page 49 and 50: March, 2007 a. When a symmetric key
Page 51 and 52: March, 2007 information. For less s
Page 53 and 54: 8. Symmetric and Asymmetric RNG key
Page 55 and 56: 15. Private ephemeral key agreement
Page 57 and 58: Key Type 12. Symmetric Key Agreemen
Page 59 and 60: March, 2007 establishment keys, see
Page 61 and 62: March, 2007 c. Restricting plaintex
Page 63 and 64: March, 2007 algorithms completely i
Page 65 and 66: March, 2007 Table 3: Hash function
Page 67 and 68: Table 4: Recommended algorithms and
Page 69 and 70: March, 2007 size is available, the
Page 71 and 72: Security life of data up to 4 years
Page 73 and 74: March, 2007 6 Protection Requiremen
Page 75 and 76: Table 5: Protection requirements fo
Page 77 and 78: Key Type Security Service Private e
Page 79 and 80: March, 2007 Crypto. Security Securi
Page 81 and 82: March, 2007 may be applied only to
Page 83 and 84: March, 2007 All cryptographic infor
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March, 2007 8. Domain parameters (e
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March, 2007 6. Destroyed Compromise
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March, 2007 a. A private signature
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2 Pre-Operational Phase 3 7 1 4 Ope
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March, 2007 8.1 Pre-operational Pha
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8.1.5.1.1 Distribution of Static Pu
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March, 2007 and then provide eviden
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March, 2007 listed in Section 8.1.5
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March, 2007 encrypting key or publi
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March, 2007 8.1.5.3.5 Intermediate
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March, 2007 of keying material and
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March, 2007 2. The application in w
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March, 2007 and the key derivation
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March, 2007 Type of Key Archive? Re
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March, 2007 All records of the enti
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March, 2007 other cryptographic inf
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March, 2007 access to information e
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March, 2007 1. Private key used to
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March, 2007 10.2 Content of the Key
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March, 2007 Management Specificatio
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March, 2007 is the same value as th
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March, 2007 If the decision is made
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March, 2007 only, and then shall be
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March, 2007 may be stored in backup
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March, 2007 and the method of key r
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March, 2007 ephemeral key pairs, an
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B.3.14.7 Key Control Information Ma
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March, 2007 to be saved. Keys for t
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[HAC] Handbook of Applied Cryptogra
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March, 2007 the owner by the CA tha
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