Part 1: General - Computer Security Resource Center - National ...

Table 4: Recommended algorithms and minimum key sizes
Algorithm security lifetimes Symmetric key
algorithms
Through 2010
(min. of 80 bits of strength)
Through 2030
(min. of 112 bits of strength)
Beyond 2030
(min. of 128 bits of strength)
(Encryption &
MAC)
2TDEA 23
3TDEA
AES-128
AES-192
AES-256
3TDEA
AES-128
AES-192
AES-256
AES-128
AES-192
AES-256
FFC
(e.g., DSA,
D-H)
Min.:
L = 1024;
N =160
Min.:
L = 2048
N = 224
Min.:
L = 3072
N = 256
IFC
March, 2007
ECC
(e.g., RSA) (e.g., ECDSA)
Min.:
k=1024
Min.:
k=2048
Min.:
k=3072
Min.:
f=160
Min.:
f=224
Min.:
f=256
The algorithms and key sizes in the table are considered appropriate for the protection of data
during the given time periods. Algorithms or key sizes not indicated for a given range of years
shall not be used to protect information during that time period. If the security life of
information extends beyond one time period specified in the table into the next time period (the
later time period), the algorithms and key sizes specified for the later time shall be used. The
following examples are provided to clarify the use of the table:
a. If information is encrypted in 2005 and the maximum expected security life of that data is
only five years, any of the algorithms or key sizes in the table may be used. But if the
information is protected in 2005 and the expected security life of the data is six years,
then 2TDEA would not be appropriate.
b. If information is initially signed in 2009 and needs to remain secure for a maximum of
ten years (i.e., from 2009 to 2019), a 1024 bit RSA key would not provide sufficient
protection between 2011 and 2019 and, therefore, it is not recommended that 1024-bit
RSA be used in this case. It is recommended that the algorithms and key sizes in the
"Through 2030" row (e.g., 2048-bit RSA) should be used to provide the cryptographic
23 40
The guarantee of at least 80-bits of security for 2TDEA is based on the assumption that an attacker has at most 2
matched plaintext and ciphertext blocks (see [ANSX9.52], Annex B).
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