Unix System Administration Handbook 1997 October/usah_oct97.iso/rfc/1900s/rfc1984.txt

Text File | 1996-08-18 | 11KB | 284 lines

Network Working Group                                                IAB
Request for Comments: 1984                                          IESG
Category: Informational                                      August 1996


  IAB and IESG Statement on Cryptographic Technology and the Internet

Status of This Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Copyright

   (C) Internet Society 1996.  Reproduction or translation of the
   complete document, but not of extracts, including this notice, is
   freely permitted.

July 24, 1996

   The Internet Architecture Board (IAB) and the Internet Engineering
   Steering Group (IESG), the bodies which oversee architecture and
   standards for the Internet, are concerned by the need for increased
   protection of international commercial transactions on the Internet,
   and by the need to offer all Internet users an adequate degree of
   privacy.

   Security mechanisms being developed in the Internet Engineering Task
   Force to meet these needs require and depend on the international use
   of adequate cryptographic technology.  Ready access to such
   technology is therefore a key factor in the future growth of the
   Internet as a motor for international commerce and communication.

   The IAB and IESG are therefore disturbed to note that various
   governments have actual or proposed policies on access to
   cryptographic technology that either:

   (a) impose restrictions by implementing export controls; and/or

   (b) restrict commercial and private users to weak and inadequate
       mechanisms such as short cryptographic keys; and/or

   (c) mandate that private decryption keys should be in the hands of
       the government or of some other third party; and/or

   (d) prohibit the use of cryptology entirely, or permit it only to
       specially authorized organizations.



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   We believe that such policies are against the interests of consumers
   and the business community, are largely irrelevant to issues of
   military security, and provide only a marginal or illusory benefit to
   law enforcement agencies, as discussed below.

   The IAB and IESG would like to encourage policies that allow ready
   access to uniform strong cryptographic technology for all Internet
   users in all countries.

The IAB and IESG claim:

   The Internet is becoming the predominant vehicle for electronic
   commerce and information exchange. It is essential that the support
   structure for these activities can be trusted.

   Encryption is not a secret technology monopolized by any one country,
   such that export controls can hope to contain its deployment. Any
   hobbyist can program a PC to do powerful encryption. Many algorithms
   are well documented, some with source code available in textbooks.

   Export controls on encryption place companies in that country at a
   competitive disadvantage. Their competitors from countries without
   export restrictions can sell systems whose only design constraint is
   being secure, and easy to use.

   Usage controls on encryption will also place companies in that
   country at a competitive disadvantage because these companies cannot
   securely and easily engage in electronic commerce.

   Escrow mechanisms inevitably weaken the security of the overall
   cryptographic system, by creating new points of vulnerability that
   can and will be attacked.

   Export controls and usage controls are slowing the deployment of
   security at the same time as the Internet is exponentially increasing
   in size and attackers are increasing in sophistication. This puts
   users in a dangerous position as they are forced to rely on insecure
   electronic communication.

TECHNICAL ANALYSIS

KEY SIZE

   It is not acceptable to restrict the use or export of cryptosystems
   based on their key size.  Systems that are breakable by one country
   will be breakable by others, possibly unfriendly ones.  Large
   corporations and even criminal enterprises have the resources to
   break many cryptosystems.  Furthermore, conversations often need to



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   be protected for years to come; as computers increase in speed, key
   sizes that were once out of reach of cryptanalysis will become
   insecure.

PUBLIC KEY INFRASTRUCTURE

   Use of public key cryptography often requires the existence of a
   "certification authority".  That is, some third party must sign a
   string containing the user's identity and public key.  In turn, the
   third party's key is often signed by a higher-level certification
   authority.

   Such a structure is legitimate and necessary.  Indeed, many
   governments will and should run their own CAs, if only to protect
   citizens' transactions with their governments.  But certification
   authorities should not be confused with escrow centers.  Escrow
   centers are repositories for private keys, while certification
   authorities deal with public keys. Indeed, sound cryptographic
   practice dictates that users never reveal their private keys to
   anyone, even the certification authority.

KEYS SHOULD NOT BE REVEALABLE

   The security of a modern cryptosystem rests entirely on the secrecy
   of the keys.  Accordingly, it is a major principle of system design
   that to the extent possible, secret keys should never leave their
   user's secure environment.  Key escrow implies that keys must be
   disclosed in some fashion, a flat-out contradiction of this
   principle.  Any such disclosure weakens the total security of the
   system.

DATA RECOVERY

   Sometimes escrow systems are touted as being good for the customer
   because they allow data recovery in the case of lost keys. However,
   it should be up to the customer to decide whether they would prefer
   the more secure system in which lost keys mean lost data, or one in
   which keys are escrowed to be recovered when necessary.  Similarly,
   keys used only for conversations (as opposed to file storage) need
   never be escrowed.  And a system in which the secret key is stored by
   a government and not by the data owner is certainly not practical for
   data recovery.

SIGNATURE KEYS

   Keys used for signatures and authentication must never be escrowed.
   Any third party with access to such keys could impersonate the
   legitimate owner, creating new opportunities for fraud and deceit.



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   Indeed, a user who wished to repudiate a transaction could claim that
   his or her escrowed key was used, putting the onus on that party.  If
   a government escrowed the keys, a defendant could claim that the
   evidence had been forged by the government, thereby making
   prosecution much more difficult.  For electronic commerce, non-
   repudiation is one of the most important uses for cryptography; and
   non-repudiation depends on the assumption that only the user has
   access to the private key.

PROTECTION OF THE EXISTING INFRASTRUCTURE

   In some cases, it is technically feasible to use cryptographic
   operations that do not involve secrecy.  While this may suffice in
   some cases, much of the existing technical and commercial
   infrastructure cannot be protected in this way.  For example,
   conventional passwords, credit card numbers, and the like must be
   protected by strong encryption, even though some day more
   sophisticated techniques may replace them.  Encryption can be added
   on quite easily; wholesale changes to diverse systems cannot.

CONFLICTING INTERNATIONAL POLICIES

   Conflicting restrictions on encryption often force an international
   company to use a weak encryption system, in order to satisfy legal
   requirements in two or more different countries.  Ironically, in such
   cases either nation might consider the other an adversary against
   whom commercial enterprises should use strong cryptography.  Clearly,
   key escrow is not a suitable compromise, since neither country would
   want to disclose keys to the other.

MULTIPLE ENCRYPTION

   Even if escrowed encryption schemes are used, there is nothing to
   prevent someone from using another encryption scheme first.
   Certainly, any serious malefactors would do this; the outer
   encryption layer, which would use an escrowed scheme, would be used
   to divert suspicion.

ESCROW OF PRIVATE KEYS WON'T NECESSARILY ALLOW DATA DECRYPTION

   A major threat to users of cryptographic systems is the theft of
   long-term keys (perhaps by a hacker), either before or after a
   sensitive conversation.  To counter this threat, schemes with
   "perfect forward secrecy" are often employed.  If PFS is used, the
   attacker must be in control of the machine during the actual
   conversation.  But PFS is generally incompatible with schemes
   involving escrow of private keys.  (This is an oversimplification,
   but a full analysis would be too lengthy for this document.)



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CONCLUSIONS

   As more and more companies connect to the Internet, and as more and
   more commerce takes place there, security is becoming more and more
   critical.  Cryptography is the most powerful single tool that users
   can use to secure the Internet. Knowingly making that tool weaker
   threatens their ability to do so, and has no proven benefit.

Security Considerations

   Security issues are discussed throughout this memo.

Authors' Addresses

   Brian E. Carpenter
   Chair of the IAB
   CERN
   European Laboratory for Particle Physics
   1211 Geneva 23
   Switzerland

   Phone: [phone]
   EMail: [e-mail]


   Fred Baker
   Chair of the IETF
   cisco Systems, Inc.
   519 Lado Drive
   Santa Barbara, CA 93111

   Phone: [phone]
   EMail: [e-mail]


   The Internet Society is described at http://www.isoc.org/

   The Internet Architecture Board is described at
   http://www.iab.org/iab

   The Internet Engineering Task Force and the Internet Engineering
   Steering Group are described at http://www.ietf.org









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