Use the same word as the previous sentence ("powerful")

Signed-off-by: David A. Wheeler <[email protected]>

Author: david-a-wheeler

secure_software_development_fundamentals.md

@@ -4666,7 +4666,7 @@ Remember that per least privilege, we want to minimize the time a privilege is a
 
 One of the large future unknowns in cryptography is the potential impact of general-purpose quantum computers. At the time of this writing, so-called *general-purpose* quantum computers exist, but they are not powerful enough to threaten current cryptographic algorithms. It is not known if such more powerful general-purpose quantum computers can be built, and if so, when that will happen.
 
-If strong general-purpose quantum computers are built, they have the potential to break all the historically popular public-key algorithms using an algorithm called *Shor’s algorithm*. As a result, researchers are developing new public-key algorithms that resist attacks from such quantum computers, an area called *post-quantum cryptography*. At the time of this writing, many such algorithms have been developed and are being evaluated.
+If powerful general-purpose quantum computers are built, they have the potential to break all the historically popular public-key algorithms using an algorithm called *Shor’s algorithm*. As a result, researchers are developing new public-key algorithms that resist attacks from such quantum computers, an area called *post-quantum cryptography*. At the time of this writing, many such algorithms have been developed and are being evaluated.
 
 In contrast, current symmetric cryptographic algorithms and hash functions are less affected by quantum computers. A quantum computer algorithm called *Grover’s algorithm* speeds up attacks against symmetric ciphers, halving their effective key bit length. That means that 128-bit AES could be broken by a quantum computer (because it would then be equivalent to a 64-bit key today), but 256-bit AES would still be secure (because it would be equivalent to a 128-bit key today). So simply using longer keys and hashes is generally expected to be adequate in a post-quantum world for symmetric cryptographic algorithms and hash functions.