IAB/IESG Statement on Cryptography

[Daniel Karrenberg <]

Dear Colleagues,

security and the use of cryptography is a major issue for further
development of the Internet.  The statement below is very well done and
quite comprehensive.  It should be distributed widely and especially to
any policymaker you know.  I also propose that RIPE formally endorse
this statement as soon as possible.

Daniel

------- Forwarded Message

Date:     Wed, 24 Jul 1996 08:21:59 +0200 (MET DST)
From:     Brian Carpenter CERN-CN brian@localhost
Sender:   ietf-request@localhost
To:       ietf@localhost
Subject:  IAB/IESG statement on cryptography

IETF,

FYI, the IAB and IESG have just requested the Internet Society
to release the attached statement to the press on our behalf.
(The copyright tag at the end is purely to protect the text
against misuse.)

We intend to publish this as an informational RFC for the record.

   Brian Carpenter

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IAB and IESG statement on cryptographic technology and the Internet
- -------------------------------------------------------------------

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.

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
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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 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.
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.)



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.

- ----
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

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

(ends)


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